This invention relates generally to the control of rodents and more particularly to a device which generates sound waves that are offensive to rats and mice.
Sound waves having frequencies of about 60 cycles per minute are known to be offensive to rodents such as rats and mice. Although it has been proposed in the past to utilize sound waves to repel rodents and other pests, the devices that have been proposed for generating sound waves have been unsatisfactory in a number of respects. Perhaps most significantly, the proposed devices require switches, thermostats, flashers, generators, phase energizers, and other complex mechanisms having moving parts that are subject to wear and require frequent inspection, maintanence and replacement. The complexity of the proposed devices also adds appreciably to the manufacturing cost and in most cases makes the cost prohibitive. The sounds generating coils are normally aligned in bucking fashion in order to cause vibrations, and they must be wired to switches such that the device is further complicated.
Typically, the sound waves are swept through a relatively large frequency range in an effort to control a wide variety of flying and crawling pests. However, none of the pests are controlled in an effective manner by this method because the frequency that is offensive to a particular pest is generated for only a small percentage of the time. Thus, the pests return during times when the offensive frequency is absent. Devices that cycle off for significant periods of time such as 5 or 10 minutes have the same problem.
Transmission of the offensive sound waves through the ground has also been proposed in order to control below ground pests. Pipe probes or anchor tubes are required for transmission of the sound waves through the ground, and components of this nature unduly complicate the structure and add to its cost. The pipe probes and anchor tubes are also susceptible to problems which can cause the device to malfunction.